A master ninja and a Portuguese priest investigate the murder of a samurai in medieval Kyoto. May 1564: When a samurai is brutally murdered in a Kyoto teahouse, master ninja Hiro has no desire to get involved. But the beautiful entertainer accused of the crime enlists the help of Father Mateo, the Portuguese Jesuit Hiro is sworn to protect, leaving the master shinobi with just three days to find the killer in order to save the girl and the priest from execution. The investigation plunges Hiro and Father Mateo into the dangerous waters of Kyoto's floating world, where they learn that everyone from the elusive teahouse owner to the dead man's dishonored brother has a motive to keep the samurai's death a mystery. A rare murder weapon favored by ninja assassins, a female samurai warrior, and a hidden affair leave Hiro with too many suspects and far too little time. Worse, the ninja's investigation uncovers a host of secrets that threaten not only Father Mateo and the teahouse, but the very future of Japan.